According to news reports, the American Arbitration Association said J.P. Morgan’s Asset Management unit purposely violated an agreement tied to the purchase of American Century in 2003, by promoting its own funds at the expense of American Century’s.

In the American Arbitration Association’s 72-page decision it stated, “J.P. Morgan breached the contract over and over again. Evidence that compels this finding and conclusion of the one-sided sales and marketing support given to J.P. Morgan Asset Management and its funds is voluminous.”

According to the arbitration panel, J.P. Morgan agreed to promote the American Century funds when it bought Retirement Plan Services in 2003. However, J.P. Morgan, which held a large minority stake in American Century’s parent company had wanted to buy the entire company. The panel said J.P. Morgan’s personnel thought if American Century funds performed worse, then the company’s value might fall, therefore making it less expensive to purchase.

After the purchase J.P. Morgan pushed in-house funds and encouraged customers to swap out of American Century funds and also awarding bonuses for selling J.P. Morgan products, the panel said.

American Century won the arbitration ruling on August 10, 2011. The award was confirmed by a Missouri state court on December 6, 2011. The award remained confidential until J.P. Morgan agreed to disclosure the information on Wednesday. The payout includes the $373 million arbitration award plus interest.

In an e-mailed statement to The New York Times, J.P. Morgan Spokeswoman Kristen Chambers said, “We disagree strongly with the arbitrators’ decision and award because, among other things, it misinterprets the contract; ignores facts favorable to us, such as the performance of certain American Century funds during the period in dispute; and ignores expert opinions that were favorable to us.”